If she still says no than she needs help so dont even bother.Yep just tell her to piss off if she is gonna tease u all the time.Thats not nice to do.How frustrating.She probably knows what shes doing to you.If i was you i would try all the approaches then if she still dont want you then just whip it out and start having a wank it will either disgust her and she will be gone like a flash or turn her the other way and either want to watch you or join in.